Existing traffic signals at intersections and along roadways utilize various traffic hardware devices to affect or monitor signalization. Generally, these devices are positioned adjacent to the intersection they impact and are frequently disposed upon traffic signal poles or arms (e.g., cameras), within a traffic control cabinet (e.g., conflict monitor unit), or in/on the roadway pavement (e.g., loop detector). Traffic control cabinets are well known within the industry and generally comprise an enclosure constructed from metal or plastic to house electronic equipment associated with a traffic signal or other traffic control/monitoring devices. For example, the National Electrical Manufacturers Association specifies various cabinet types which may be effective for housing embodiments of the present invention. Some specific, non-limiting examples include a NEMA P-44 or Model 332 marketed by Trafficware®, Econolite®, McCain®, etc. As used herein, “traffic control cabinet” may also refer to a control device disposed adjacent to a railway or at-grade railway crossing.
Within a traffic control cabinet, a control assembly may be used to manipulate the various phases of a traffic signal. The operation of the traffic signal may be adaptive, responsive, pre-timed, fully-actuated, or semi-actuated depending upon the hardware available at the intersection and the amount of automation desired by the operator (e.g., municipality). For instance, cameras, loop detectors, or radar may be used to detect the presence or location of a vehicle. In response to a vehicle being detected, a traffic signal controller may alter the timing of the traffic signal cycle, for example, to shorten a red light to allow a waiting vehicle to traverse the intersection without waiting for a full phase to elapse. As another example, a traffic signal controller may extend a green phase if it determines an above-average volume of traffic is present and the queue needs additional time to clear before initializing a red phase.
Motorists are frequently concerned with the duration of drive times and seek to identify routes that may reduce overall travel time. Often this includes avoiding intersections which are characterized by either long red phases or excessive traffic congestion causing a queue too large to clear during a single signal cycle. However, the nature of traffic congestion makes it very difficult to predict and therefore difficult to avoid. For instance, traffic collisions and stalled vehicles may occur anywhere within a traffic network, causing a localized disturbance in traffic flow which may ripple throughout the system.
Additionally, not all disruptions in traffic flow are caused by substantial events such as collisions and breakdowns. In many instances, minor delays are created by human behavior which may aggregate into significant delays. For instance, a minor delay may be created following a red light phase during which a driver may not instantly react to the fact that the light has changed to green. This may be caused by the driver being distracted or simply by the human delay in perceiving the change and then reacting to it. Although a single instance of such a delay may be only a few seconds or even less than one second, the aggregated effect of dozens or hundreds of these delays throughout a corridor may add up to a consequential delay.
Safety is a primary concern in the operation of motor vehicles. In some instances, a driver may be distracted by a mobile device, a passenger in the vehicle, or an interesting object or occurrence outside the vehicle. For instance, lingering car accidents or traffic stops by police often distract uninvolved drivers as they pass by. Unfortunately, distractions frequently lead to collisions, injuries, and fatalities.
Another problem in the industry involves security vulnerabilities in communication protocols. This is a concern in a variety of contexts, including connected, autonomous or semi-autonomous vehicles. For example, messages between one traffic signal and another, or between a traffic signal and a vehicle may be spoofed or otherwise accessed by unauthorized parties. One concern in this regard is that a communication may be sent to a vehicle (or a device associated with a vehicle) emulating a message from a traffic signal but which contains false information. For example, the message may indicate that a given approach to an intersection is currently under a green phase when in fact it's a red phase (or vice versa). Such communications may cause traffic collisions. A means of securing and authenticating communications from traffic signals is needed to prevent such spoofing or unauthorized access.